A clear need exists for the development of advanced power ources and recharging options for implanted electro-medical devices. The useful lifetime of most implants is constrained by the longevity of the power source. When an implanted primary (non-rechargeable) battery has discharged to a predetermined threshold, surgery must be scheduled to replace the battery or the entire device, at considerable cost, patient distress, and about a 2% chance of infection. Implantable devices that might use rechargeable batteries include a growing variety of neurostimulators to counteract Parkinson's symptoms, for chemotherapy, to electrically stimulate the stomach, throat, urinary tract and other muscles, to deliver pain medication, and for implanted pressure and temperature sensors whose use will proliferate quickly. All of these applications place demands on electrical power within the body. A novel new method for recharging secondary batteries can overcome some of the difficulties of the present method, which includes MRI incompatibility. The wireless power transmission technology being developed is based on well known principles of ultrasound, which is know for its safety in diagnostic applications. The potential advantages include smaller transmitters and receivers, elimination of electromagnetic interference and heating of metal parts, and transmission of power to deeper sites in the body. The latter will drive new applications. Our principal goals and specific aims are to demonstrate its ultimate capabilities in vivo, facilitate more rapid recharging thus fostering patient compliance, comply with FDA safety regulations, and move the technology forward to the prototype stage, ready to be made into a useful product. We will do this by increasing its power delivery, showing that any temperature rise is kept within FDA guidelines, developing alignment and cooling techniques, and constructing small and inexpensive components. This technology will support the NIH mission, advancing its goals to improve human health and reduce health care costs by: 1) alleviating the distress, pain, and complications by reducing battery replacement operations, 2) increasing functionality of the implant by providing more power for diagnostic output or burst mode operation, 3) improving patient compliance, and 4) reducing the number of expensive operations that replace batteries and other components. PUBLIC HEALTH RELEVANCE: This new wireless recharging technique will result in increased longevity and capability of implanted batteries and will advance several public health goals by: 1) alleviating distress, pain, complications and cost by reducing the number of battery replacement operations, 2) increasing functionality of the implant by providing more power for diagnostic output or burst mode operation, 3) improving patient compliance.